Dave Sweet, whose obsessive tinkering 60 years ago in search of a better way to ride a wave resulted in a surfboard revolution — the first board with a core of polyurethane foam, still the leading choice of surfers from Oahu to the Maldives — died on May 18 in Los Angeles. He was 86.
The cause was kidney failure, his son, Greg, said.
Beyond the circumscribed world of surfing, Mr. Sweet and his contribution to history are largely unknown. A more familiar name is Hobie Alter, who also developed foam boards, began selling them in 1958 and was responsible for mass-producing them and fueling their popularity during the boom that began in the late 1950s.